Liquid level indicating apparatus



April 19, 1949. D. H. ANNIN LIQUID LEVEL INDICATING APPARATUS 2 Shoots-Sheet 1 Filed Juno 4, 1945 FIEB J ATTORNEY m a w z. L1 w .1 up F M v. y H w mi 2 m r n H n L a a m a m x m B P, m H "N April 19, 1949. n. H. ANNIN LIQUID LEVEL INDIGATING APPARATUS Filed June 4, 1945 2 Sheets-Sheet 2 FIE-3.33...

- mmvron. Doug/as H firm/n ATTORNEY Patented Apr. 19, 1949 LIQUID LEVEL inprca'rinc arra'rus Douglas H. Armin, Uakland, fialifi, assignor to Grove Regulator Company, Oakland, Calif., a corporation of California Application June 4, 1945, Serial No. 597,554

2 Claims. (Cl.

This invention relates generally to apparatus for indicating or measuring the level of liquid in a tank or vessel.

It is an object of the invention to provide apparatus of the above character capable of ac- :urately indicating or measuring liquid level, and which is adapted for use with closed tanks operating at relatively high pressures and temperatures.

A further object of the invention is to provide liquid level indicating means which will dispense with use of conventional packing glands, diaphragms, torsion tubes or like sealing means between relatively movable parts.

A further object of the invention is to provide a novel type of pneumatic indicating means operating upon the null principle, for the purpose of indicating or measuring variations in the liquid level.

Additional objects of the invention will appear from the fellowing description in which the preferred embodiment has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure l is a side elevational view partly in cross-section, illustrating apparatus incorporating the present invention.

Figure 2 is an enlarged detail in section illus-v trating suitable means for connecting certainparts of the apparatus to a liquid tank or Vessel.

Figure 3 is an enlarged detail in section illustrating suitable pneumatic balancing means of the null type incorporated in conjunction with the apparatus.

Figure 4 is an enlarged view in section showing a modified type of pneumatic balancing means.

The apparatus illustrated in the drawing consists generally of a closed vertical tube it having special connections with a tank I l, and operatively connected witha pneumatic device E2. The pneumatic device may connect to any one of a variety of devices or instruments for effecting a measurement, indication or response in accordance with liquid level, as for example a pressure gauge [3. Device i2 is of the null type, operated by very slight vertical movements of the tube it, and functions to automatically restore tube it to normal balanced position after the balance has been upset by an increase or decrease of the amount of water in the tube.

The connection between tube l and the tank l i completely eliminates conventional expedients such as packing glands, torsion tubes, diaphragms and the like, and makes use of simple straight parallel metal tubes [4. These tubes are rigidly attached to one side wall of the tube ID, as by means of welding or silver soldering, and they are also rigidly attached to the side wall of the tank H, in such a manner that the tube i0 is placed in communication with the interior of tank H at spaced points.

In order to protect tubes l0 and it from injury, and for the mounting of certain parts to be presently described, tubes M are enclosed within the pipes l6, which in turn have suitable rigid attachment to the side wall of the tank. In the particular construction illustrated in Figure 2 a union i8 is provided, with corresponding ends of r the tubes l4 and [6 being attached by weldin or soldering to the union part 19. Union part i9 is clamped by ferrule 2| to the union part 22, which in turnis shown with a threaded connection into the side wall of tank I l.

The outer ends of pipe l6 connect with a suitable frame or housing for the tube l0, which can consist for example of the vertical channel 23. The upper and lower end portions 24 and 26 of this channel are bent laterally to extend above and below the ends of tube [0. A cover 21 of sheet metal can be attached to the channel 23, thuscompleting a protective housing for the tube It.

The upper end of the tube I0 is preferably connected to suitable counterbalancing means whereby the weight of this tube can be balanced out. For this purpose the upper end of tube ID has a pivotal connection 28 with a rod 29, which in turn extends through the compression spring ill. The lower end of spring M is seated upon the upper channel part 2 -3, while its upper end is engaged by a washer beneath a nut 32, which is threaded on rod 29. Thus by turning nut 32 the counterbalancing efiect of spring 3i can be adjusted to a desired value.

The pneumatic device l2 shown in Figure 3 consists of a base member 36 mounted upon the channel part 26. Mounted upon the member 38 there is a shell 31 having its upper end closed by the plate 38. Two Sylphon tubes 39 and W are disposed within the shell 31, and a third Sylphon M is mounted above the plate 38. The lower ends of Sylphons 39 and 40 are secured to and sealed with respect to the base plate 36,.

and their upper ends are secured to and sealed with respect to a thrust plate 42. Within the Sylphon 10 there is a compression spring 43 which normally urges plate 42 upwardly.

Sylphon ll has its lower end secured to and sealed with respect to plate 38, and its upper end is secured to and sealed with respect to plate 44. The center of plate 44 carries themember 48 which has abutting engagement with the lower end of tube l0. Within the Sylphon 4| there is another relatively smaller Sylphon 41,'which has its lower end secured and sealed with respect to plate 38, and its upper end secured and sealed with respect to plate 44.

Pipe 48 is connected to a suitable source of high pressure air or like gas, and is directly connected with the space 49 in base plate 36. This space has restricted communication with the space 5| surrounding Sylphon 39, through a suitable restricted orifice such as is formed by the tube 52 which is carried upon the inner end of the removable plug 53. Tube 52 has its one end in communication with space 49, and near its other end it is provided with a small lateral orifice 54', which permits restricted communication with space 5|.

Space 5| surrounding Sylphon 39 is in valve controlled communication with the space 56 within the Sylphon 41. Thus within Sylphon 41 there is a tube 51 which communicates with the space 5| at a point above the center of plate 42, and which at its upper end is provided with the annular valve surface 58. This valve surface or seat is adapted to engage and cooperate with the adjacent surface 59, carried by the plate 44 within tube 41. Thus slight raising movement of plate 44 results in venting of air from tube 51 into the space 56, and downward movement to cause engagement of surfaces 58 and 59 interrupts or restricts such communication. Space 56 is vented to the atmosphere through the duct 6|.

The pressure gauge [3, which indicates the liquid level, is connected to base plate 36 by pipe 63. This pipe communicates through duct 64 with the space 66 within the Sylphon 4|. It also communicates through'duct 61 with the space 68 within the Sylphon 46. Flow of air from space 49 into space 66 is controlled by a valve member 69 cooperating with the stationary seat 1|. This valve member is urged upwardly towards closed position by the compression spring 12.

Valve member 69 carries an extension 13, the upper end of which forms the valve member 14. A seat 16 cooperates with valve member 14, and is formed upon the lower end of an extension 11 which extends downwardly from the center of plate 42. The valve orifice through seat 16 communicates with space 18 between the Sylphons 39 and 40, through the ducts 19 and 8|. Space 18 is continuously vented to the atmosphere through duct 82.

Assuming an initial condition in which all of the valve members of device |2 are closed, it will be apparent that a downward movement of plate 42 results in opening of valve member 69, whereas upward movement of plate 4'2 causes opening of valve member 14. The pressure existing in chambers 66 and 68 determines the reading of the pressure gauge 3.

Operation of the apparatus described above can be explained as follows: Counterbalancing spring 3| is adjusted to completely counterbalance the weight of tube l0 whereby without liquid within the same the tubes l4 are completely unstressed. Liquid entering tube ID will take a level corresponding to that within the tank, due to the free communication of this tube with the tank through thehorizontal tubes l4. Tube 48 is connected to a source of air which should be at a pressure generally above the highest pressure reading of gauge I3. Under conditions of equilibrium gauge l3 indicates a pressure corresponding to the level of liquid within tube i0 and tubes H are substantially unstressed. Assuming that there is a drop in liquid level, tube I0 is made lighter and as a result there is a slight upward movement of this tube well within the limits of lateral flexibility of the metal tubes |4. Such slight upward movement causes an opening of valve surface 59 with respect to seat 58, and as a result an increased amount of air is vented from chamber 5| through tube 51, and to the atmosphere through passage 6|. Because of the restricted orifice 54 this causes an immediate drop in pressure within chamber 5|,-

which results in a slight upward movement of plate 42 to open valve member 14' with respect to seat 18. Such opening movement increases venting of air from chamber 68 (and also chamber 66) past valve 14 through ducts 19 and 8| and from thence through chamber 18, to the atmosphere through duct 82. Thus a corresponding change in the indicating pressure occurs, which is immediately registered by the gauge l3. Drop of pressure in chamber 66 serves to restore the plate 44, and likewise the tube It], to approximately its initial position. Should there be an increase in liquid level tube Ill is made heavier, and as a result there is slight downward movement of the same well within the limits of flexibility of tube l4. Such downward movement effects temporary closing or complete shut off of valve seat 58 with respect to surface 59, thus causing pressure to build up in chamber 5|. Building up of pressure in this chamber causes plate 42 to be moved downwardly thus causing an opening of valve member 69 with respect to seat i1, to admit high pressure air from pipe 48 into space 68. Sufficient air is admitted in this fashion until equilibrium conditions are restored, and restoration of equilibrium involves an increase of pressure in chamber 66 to again restore tube Hi to its initial position. The new pressure in chambers 66 and 68 is indicated by the reading of pressure gauge i3.

The pneumatic device |2 described above is capable of supplying adequate amounts of air to an extended pipe 63, thus minimizing lag in the readings of the gauge i3, should this gauge be located a considerable distance away.

A particular feature of my invention is the use of simple horizontal parallel tubes l4 connecting the vertical tube ID at spaced vertical points with the tank If. These tubes |4 together with tube Hi can be made of suitable metal, such as stainlesssteel, phosphor bronze or the like, capable of withstanding relatively high pressures. With a pneumatic device I 2 of the null type, lateral flexibility of these tubes can be at a minimum. In

factvertical movement of the tube it! within a latitude of 0.02 inch will sufllce for operation of the device I 2 for full range indication of the gauge l3. As previously explained the counterbalancing spring 3| offsets the weight of the tube Ill, and the normal balanced position for equilibrium of device l2 corresponds to completely unstressed position of tubes I4. Nominal stressing occurs well within th elastic limits of tubes |4 during temporary periods when the balance has been disturbed and the pneumatic device |2 is being restored to balanced condition. It will be evident that this makes for accurate response while at the same time it enables application of relatively high pressures where conventional equipment would be impractical. Also the apparatus is applicable to high temperature connect passage I02 with the space services, with or without corresponding high pressure.

Figure 4 illustrates a simplified type of pneumatic balancing device which is likewise of the nullv type. This device eliminates the booster arrangement incorporated in Figure 3. Briefly the simplified device of Figure 4 consists of a base or body member IOI which has a passage I02 adapted for connection with the air supply pipe 40 (Figure 1) and also a passage I03 adapted for connection with pipe 03 and gauge I3. A Sylphon I04 is mounted upon base MI, and the upper end plate I of this Sylphon has a thrust member I0I which engages the lower end of the tube I0. Mounted on and extending upwardly from base I0l there is a nozzle I08 having its upper end forming a seat I09 for cooperation with the disc III on the plate I00. The orifice through seat I09 vents to the atmosphere through the nozzle passage II 2. Duct III and restricted passage Ill HS in Sylphon I00. Duct II also connects passage I03 with space H5. 1

Operation of the device shown in Figure 4 is somewhat similar to that of Figure 3 except for elimination of the booster function. Normally the device assumes a balanced position whereby the pressure within the Sylphon assumes a value which is transmitted to the gauge, and which indicates the liquid level in tube I0. This balance "is maintained by controlled venting of air in chamber II5 through the nozzle passage II2. Assuming an increase in liquid level, tube I0 moves downwardly a slight amount to restrict venting past seat I09 and thus causing pressure to be built up in chamber H5 until pressure is suflicient to again balance tube I0 and restore this tube to normal balanced position. This increased pressure is transmitted to the gauge as previously explained. A lowering of the liquid level likewise upsets the balance of the device by causing an upward movement of disc III which results in increased venting from chamber II5 to the atmosphere. When equilibrium is restored, the tube I0 has again been caused to return to a normal position and the pressure now being maintained in chamber II! as read by the pressure gauge I0, indicates the lower level. Irrespective of the liquid level being indicated, the normal balanced position of tube I0 is substantially the same wh'ereby tubes I4 remain substantially unstressed. Thus changes in internal pressure or temperature have no effect upon accuracy of indication, because they do not serve to create forces applied to the tube I0 and tending to raise or lower the same.

I claim:

1. In liquid level indicating apparatus adapted for use with a liquid tank having an upright side wall, a pair of ported fittings adapted to be attached to the side wall of the tank for communicating with the interior of the same at vertically spacedpoints, a pair of straight concentric tubular metal members attached to each fitting and extending horizontally from the same. the inner tube of each pair being in communication with the associated fitting port and being capable of slight lateral bending within its elastic limit, a vertically extending frame having its upper and lower end portions attached to the ends of the outer tubes of each pair, a closed tubular container of substantial height disposed vertically within the frame and having its upper and lower end portions rigidly attached to the adjacent ends of the inner tubes, and pneumatic balancing means of the null type carried by the frame and having a thrust transmitting member operatively connected to said tubular member, said last means being responsive to the amount of liquid in the container and serving to maintain the normal level of the container in such a position that the inner tubes of each pair are normally substantially unstressed.

I tube of each pair being relatively rigid, the axes of the two pairs of tubes being parallel, a vertically extending frame having its upper and lower end portions attached to the adjacent ends of the outer'tubes of each pair, a closed tubular container of substantial height disposed vertically within the frame and having its upper and lower portions rigidly attached to the adjacent ends of the inner tubes, a spring means carried by the upper portion of the frame and acting between the frame and the tubular container to oppose th weight of the latter, and pneumatic balancing means of the null type mounted on the lower portion of the frame and having a thrust transmitting member operatively connected to said tubular container, said last means being responsive to the amount of liquid in the container and serving to maintain the normal level of the container in such a position that the parallel horizontal tubes are normally substantially unstressed.

DOUGLAS H. ANNIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 274,103 Ayres Mar. 20, 1883 1,237,478 Clift Aug. 21, 1917 1,559,357 O'Neill Oct. 27, 1925 2,040,357 Chalatow May 12, 1.936 2,248,322 Annin July 8, 1941 2,342,696 Rover Feb. 29, 1944 FOREIGN PATENTS Number Country Date 670,571 Germany Jan. 20, 1930' 676,406 France Nov. 28, 1929 

